Abstract

Methods Blood and milk samples were collected before and 3–4 h after once daily routine subcutaneous injection of 2500 IU dalteparin. Anti-Xa activity was measured by an assay utilizing prolonged clotting times in plasma or breast milk as an index of LMWH activity.

Results Plasma anti-Xa activities ranged from 0.074 to 0.308 IU ml−1 of plasma. Anti-Xa activities in breast milk ranged from < 0.005–0.037 IU ml−1 of milk. This is equivalent to a milk/plasma ratio of < 0.025–0.224.

Conclusions Therefore, it appears highly unlikely that puerperal thromboprophylaxis with LMWH has any clinically relevant effect on the nursing infant.